<div class="content">
    <textarea id="pre">
		.flex{
			display:flex;
		}
		.flex-center{
			align-items: center;
			justify-content: center;
		}
		.flex-sub {
			flex: 1;
		}
		.align-start {
			align-items: flex-start;
		}

		.align-end {
			align-items: flex-end;
		}

		.align-center {
			align-items: center;
		}
		.justify-start {
			justify-content: flex-start;
		}

		.justify-end {
			justify-content: flex-end;
		}

		.justify-center {
			justify-content: center;
		}

		.justify-between {
			justify-content: space-between;
		}

		.justify-around {
			justify-content: space-around;
		}
	</textarea>
</div>